An energy harvester is a device that converts mechanical movements, such as vibrations, oscillations or other mechanical motions into electrical energy. This electrical energy can then be stored or used by other devices. Thus, an energy harvester could produce useful electrical power from mechanical movements. For example, the vibrations of an air duct could be converted to electrical energy by an energy harvester and the electrical energy could then be used to power a sensor that measures the temperature of air in that duct. Therefore, the sensor will not require electrical wiring to a remote source of power or periodic battery changes.
Conventional technology uses a schottky diode bridge (comprised by diodes D1˜D4) and a boost converter to convert the electrical energy into desirable voltage levels to power various loads, as shown in FIG. 1. However, the schottky diode bridge is too lossy. In addition, when the electrical energy generated by the energy harvester is low, e.g., 0.5V, the schottky diode bridge can not kick startup, which limit the use of the electrical energy with low voltage.